A change in the lane layout in Great North Road, New Lynn, marks a significant milestone in the installation of a new culvert under the road. This is designed to manage future flood-flows of the kind that swept away part of the road and resulted in an adjacent building needing to be demolished earlier this year.
Since April, Great North Road has been reduced to three lanes with the fourth lane being closed off to allow the existing culvert to be repaired and a new one installed above it. With the completion of the first stage of the works, the southern lane will now be closed and all traffic shifted over to the north side of the road to allow the remainder of the new culvert to be installed on the upstream side. There will still be three lanes available.
This change in road layout is scheduled to occur on Tuesday 26 September but this will be dependent on weather and unforeseen engineering considerations.
Whau Local Board Chair Tracy Mulholland says it’s great that progress is being made.
“I’m glad the first stage of works is complete on the culvert," she says.
"I look forward to when the project finishes so that the pressure is eased on local businesses and traffic.”
Drivers will not notice much difference as a result of the changeover. The road will continue to operate with two city-bound lanes and one westbound, but they will now be on the northern side of the road. However, motorists are asked to take additional care.
Pedestrians will see a more obvious change. From the changeover, they will be crossing the construction site on the north (Bike Barn) side of the road once the reconfigured road is opened. Pedestrian detour signs and barriers will be in place to clearly show the new route.
The floods of March and April were caused by extreme weather events that overwhelmed the existing culvert, which was installed in the 1940s. Contractors to Auckland Council’s Healthy Waters business unit have now repaired and strengthened this culvert. It will remain in use to drain normal water flows and allow the passage of fish and other aquatic animals.
A second culvert is now being installed above the original. If there is a repeat of very high flood-flows, this new culvert will automatically come into effect and prevent the waters from rising to the point where they overflow the road.
A state-of-the-art stormwater treatment system has been installed underground alongside the culvert. This will clean up the storm-water run-off from Great North Road and the Titirangi Road intersection before it discharges into the Rewarewa Creek. In addition, a small park will be created over the new culvert outlet, where seating will be provided in a landscaped environment and from where an interesting view over the creek will be seen.
